The increase in growth hormone (GH) secretion can be as much as three-fold increase in just 1 day of fasting and up to 10-fold increase in 5 days.
For practicality sake, 12-24 hr intermittent fasting (IF) would suffice.
Increased secretion of GH is triggered by low sugar levels in the blood. GH intervenes by increasing blood sugar by using glucose stored in the liver. Thus, GH is an important component of metabolism.
Increased secretion can be further achieved by exercising during a fasted state, by helping to deplete blood glucose levels faster and is better achieved with high intensity workouts. It can also be achieved with low intensity cardio workouts in a fasted state but this low intensity cardio needs to be longer.
Exercise on its own (without fasting) can result to 2 fold increase in GH secretion if done intermittently during throughout a 24 hr period.
GH has protective effect against loss of muscle mass as well as ketones and a component in hypertrophy (muscle-building). This is why I prefer and advice to workout in a fasted stated without eating anything if you're not burning a total of over 1,000 Calories in a workout session(s) for increased GH and ketone levels.
Exercising in a fasted state also results in higher GH levels immediately after exercise and this will help you build muscles if you eat protein-rich and high glycemic, high carb foods immediately or soon after exercise.
Finally, increased GH secretion can result to increased rate of fat burning.
Ironically, GH is known to reduced perceived stress. And the endorphins released from exercise can really help rest the mind at the end of a stressful week. The quality of sleep I get is perfect on the other-hand, albeit with lots of vivid dreaming.
What could reduce GH secretion:
- Sedentary lifestyle
- Age. The older we get, the less GH we make but again, this may depend on a lot of factors, not just genetics.
- Overweight/obese.
- Anti-placebo effect. (if you don't believe or strongly doubt anything I said here

) It might actually be sufficient to nullify the positive outcomes if you attempt to do any of the methods I mentioned.
Only in the beginning. But as you get used to it, you may not even need recovery anymore as I am now. Do note that GH secretion will increase further as your body adapts and the muscles will get more efficient at repairing itself and increased GH and ketones may even completely prevent muscle tissue damage.
I do all kinds of workouts each week in different days. Long and low to moderate intensity cardio (running and cycling), short and high intensity sessions (cycling), and weight lifting for strength-resistance.